The invention is directed to a process for the production of a sedimentation stable antifoam agent for aqueous systems having a long-lasting activity.
It is known from Chevalier U.S. Pat. No. 3,113,930 to produce an antifoam agent by heating a finely divided filler such as finely divided silica with a multiple excess of a liquid dimethylpolysiloxane to above 350.degree. C. and to emulsify with water while employing a special emulsifier.
From German Pat. No. 1769940 it is known to produce an antifoam agent for aqueous alkaline liquids by heating to a temperature between 100.degree. and 300.degree. C. a mixture of at least 70 weight % of an organosiloxane polymer having a viscosity of about 5 to about 100,000 centistokes, measured at 25.degree. C., together with at least 0.5 weight % of a finely divided inorganic filler, such as, e.g. silica, and 0.01 to 1 weight % of basic catalyst.